bootstd: Expand boot-ordering test to include USB

Scan the USB bus as well, so we can check that different uclasses work
correctly in boot_targets

update the function comment with more detail.

Signed-off-by: Simon Glass <sjg@chromium.org>
Tested-by: Ivan T.Ivanov <iivanov@suse.de>
diff --git a/test/boot/bootdev.c b/test/boot/bootdev.c
index 6b29213..7228f54 100644
--- a/test/boot/bootdev.c
+++ b/test/boot/bootdev.c
@@ -190,12 +190,21 @@
 BOOTSTD_TEST(bootdev_test_any, UT_TESTF_DM | UT_TESTF_SCAN_FDT |
 	     UT_TESTF_ETH_BOOTDEV);
 
-/* Check bootdev ordering with the bootdev-order property */
+/*
+ * Check bootdev ordering with the bootdev-order property and boot_targets
+ * environment variable
+ */
 static int bootdev_test_order(struct unit_test_state *uts)
 {
 	struct bootflow_iter iter;
 	struct bootflow bflow;
 
+	test_set_skip_delays(true);
+
+	/* Start up USB which gives us three additional bootdevs */
+	usb_started = false;
+	ut_assertok(run_command("usb start", 0));
+
 	/*
 	 * First try the order set by the bootdev-order property
 	 * Like all sandbox unit tests this relies on the devicetree setting up
@@ -213,12 +222,14 @@
 	bootflow_iter_uninit(&iter);
 
 	/* Use the environment variable to override it */
-	ut_assertok(env_set("boot_targets", "mmc1 mmc2"));
+	ut_assertok(env_set("boot_targets", "mmc1 mmc2 usb"));
 	ut_assertok(bootflow_scan_first(NULL, NULL, &iter, 0, &bflow));
 	ut_asserteq(-ENODEV, bootflow_scan_next(&iter, &bflow));
-	ut_asserteq(2, iter.num_devs);
+	ut_asserteq(3, iter.num_devs);
 	ut_asserteq_str("mmc1.bootdev", iter.dev_used[0]->name);
 	ut_asserteq_str("mmc2.bootdev", iter.dev_used[1]->name);
+	ut_asserteq_str("usb_mass_storage.lun0.bootdev",
+			iter.dev_used[2]->name);
 	bootflow_iter_uninit(&iter);
 
 	return 0;